1. Field of the Invention
The present invention relates to a liquid crystal device used as a display device and the like and a method for fabricating the same. More particularly, the invention relates to a liquid crystal device with excellent display quality which is free from light scattering from spacers, and a method for fabricating the same.
2. Description of the Related Art
Spacers are conventionally used to keep uniform the gap between a pair of substrates (cell gap) of a liquid crystal device. Such spacers are typically beads or fibers with a fine grain diameter which are sprinkled on one of the substrates during the fabrication of the liquid crystal device. The method for fabricating a liquid crystal device including sprinkling beads as the spacers, for example, is so simple that beads or fibers have been used as spacers for most conventional liquid crystal devices.
FIG. 3 shows an example of such conventional liquid crystal devices. The liquid crystal device includes a substrate 19 having thin film transistors (TFTs) 20 and pixel electrodes 21 formed thereon (hereinafter, referred to as an active matrix substrate) and a substrate 18 having counter electrodes 22 formed thereon (hereinafter, referred to as a counter substrate) disposed to face each other. A liquid crystal layer 26 is interposed between the counter substrate 18 and the active matrix substrate 19. Liquid crystal alignment films 23 and 24 are formed on the surfaces of the active matrix substrate 19 and the counter substrate 18, respectively, facing the liquid crystal layer 26. Spacers 25 are provided to keep uniform the cell gap between the counter substrate 18 and the active matrix substrate 19.
A liquid crystal device using spacers other than beads and fibers is proposed in Japanese Laid-Open Patent Publication No. 6-67135, for example. The technique disclosed in this publication includes transcripting pre-patterned column spacers. More specifically, the technique includes: forming alignment films on surfaces of an active matrix substrate and a counter substrate; rubbing the alignment films; forming column spacers made of a black resin on predetermined positions of a substrate which is neither the active matrix substrate nor the counter substrate; transcripting the spacers to non-pixel portions of the counter substrate (e.g., portions to be located above gate and data lines); disposing the active matrix substrate and the counter substrate having the transcripted spacers thereon to face each other; and filling the gap between the substrates with a liquid crystal material to form the liquid crystal layer.
The above conventional techniques have the following problems. Although the method including sprinkling beads or fibers as spacers is simple, the density of sprinkled spacers tends to vary from place to place. This often makes it difficult to keep the cell gap uniform and generates display defects due to aggregation of spacers. As for the method including transcripting patterned column spacers, it is difficult to form spacers precisely at predetermined positions due to insufficient alignment precision and shrinking of the substrates.
In recent years, a very fine technique has been demanded for liquid crystal devices to achieve the size of each pixel as small as 100 .mu.m.times.100 .mu.m or less. As a result, light scattering from spacers with a diameter of about 5 .mu.m or liquid crystal molecules adjacent to the spacers has become a problem to be overcome. The above conventional techniques fail to overcome this problem. A method including coloring spacers has been proposed to reduce the light scattering from spacers. This method, however, has problems such as a reduction in reliability and display characteristics of the liquid crystal device due to migration of impurities from the spacers to a liquid crystal layer, and therefore has not put into practical use as of today.
In view of the foregoing, a liquid crystal device with excellent display quality which is free from light scattering from spacers and a simple method for fabricating such a liquid crystal device are desired.